Electronic devices typically employ electronics and generally contain electrical circuitry for conducting electrical current which, in turn, generates thermal energy (i.e., heat). Many electronic devices often employ electrical circuitry in the form of integrated circuitry provided on a printed circuit board and packaged within a housing for protecting the electrical circuitry from exposure to moisture and physical contact. The generated thermal energy within the housing generally results in increased temperature. Excessive heat build-up may cause reduced performance including electrical circuit failure. Thus, it is desired to dissipate thermal energy away from the electronic device to ensure proper operation of the device.
Conventional techniques for dissipating thermal energy away from an electronic device include the use of a thermally conductive heat sink supported in contact with a packaged integrated circuit component. Typically, this technique includes mounting the heat sink onto a printed circuit board which contains surface mount electronic packages in thermal communication with the heat sink. Other conventional approaches for cooling electrical devices employ a fluid cooling medium such as air or liquid passed in thermal communication with the heat generating circuitry. The cooling fluid is typically circulated with a fan or pump.
One proposed electronic assembly employs a piezo fan for circulating a cooling fluid. One example of such use of a piezo fan is disclosed in U.S. patent application Ser. No. 11/191,822, filed on Jul. 28, 2005, now U.S. Pat. No. 7,307,841, assigned to the assignee of the present application, which is hereby incorporated herein by reference. The aforementioned piezo fan is a fluid circulator located within a heat sink housing for circulating cooling fluid in close relation to electrical components to enhance the heat transfer cooling of the electronic device. The piezo fan includes a piezoceramic with an overlying electrode and an underlying electrode and a fan blade adhered to one side. The electrodes are electrically energized to create a polarization field through the piezoceramic with causes the piezoceramic to expand or contract which induces the fan blade to stretch or bend. By reversing the electric field, a fanning oscillation effect is produced to circulate the cooling fluid. One example of a commercially available piezo fan is Model No. RFN1-005, commercially available from Piezo Systems, Inc.
While conventional piezo fans and other fluid circulators produce fluid circulation to enhance the thermal energy transfer, such devices often require additional drive circuitry. For example, the piezo fan typically requires a suitable voltage supply and a sinusoidal oscillator to power the electrodes. This may result in added cost and size constraints. The resulting fluid flow achieved with such prior known circulators may be insufficient to achieve optimal cooling for some applications.
It is therefore desirable to provide for a fluid circulator that enables the realization of enhanced cooling of heat generating electronic devices. In particular, it is desirable to provide a fluid circulator that sufficiently circulates fluid coolant with a device that minimizes the cost and complexity of the fluid circulator.